Low Sodium Levels at Hospital Admission Increase Mortality Risk

Hyponatremia at time of hospital admission also increases patients' length of stay.

Hyponatremia at the time of hospital admission is associated with an increased risk of death and longer in-patient stays, according to a new study.

Louise Balling, MD, of the Department of Cardiology, Rigshospitalet, University of Copenhagen, Denmark, and colleagues studied 2,960 patients older than 40 years who were admitted to a hospital in Greater Copenhagen.

Hyponatremia, defined as a plasma sodium level below 137 mmol/L at hospital admission, was present in 1,105 patients (37.3%). Patients had a median follow-up period of 5.16 years.

The 1-year mortality rate was higher for patients with hyponatremia than in those with normonatremia (27.55 vs. 17.7%), the researchers reported online ahead of print in the Internal Medicine Journal.

Hyponatremia independently predicted a significant 60% and 40% increased risk of short- and long-term all-cause mortality after 1 year and after the entire observation period, respectively, according to the investigators.

Patients with hyponatremia had a hospital stay of 7.6 days compared with 5.6 days for those with normonatremia, a significant difference between the groups.